Interlaced crosstalk controlled traces, vias, and capacitors

ABSTRACT

A multilayer printed circuit board having a stackup including an upper half of the stackup and a lower half of the stackup, the multilayer printed circuit board having a top exposed surface and a bottom exposed surface, a first trace and via structure, having one portion disposed on the top exposed surface and another portion disposed within the upper half of the stackup, a second trace and via structure, having one portion disposed on the top exposed surface and another portion disposed within the upper half of the stackup, and first electrical components and second electrical components disposed on the top exposed surface of the multilayer printed circuit board and associated, respectively, with the first trace and via structure and the second trace and via structure, wherein the first electrical components are mounted orthogonally with respect to the second electrical components.

TECHNICAL FIELD

The present disclosure relates to multi-layer printed circuit boardarchitecture and layout.

BACKGROUND

Computers are everywhere in today's society. They come in all differentvarieties and can be found in places such as automobiles, laptops orhome personal computers, banks, personal digital assistants, cellphones, and servers. In addition, as computers become more commonplaceand as software becomes more complex, there is a need for computingdevices to process more data at faster speeds using a smaller packageand less power. As such, the area of a printed circuit board (PCB) of acomputing system utilized by the components and portions of a givencomputing system becomes a highly valuable commodity. In general, theless area of the PCB a computing system circuit uses, the smaller thecomputer system package may be. Alternatively, area not utilized by acomputer system circuit may be used to enhance the circuit's performancethrough additional components of the circuit.

However, placing components or conductors of the PCB near each other mayresult in negative consequences in the performance of the circuit. Forexample, vias provide electrical connections between layers of amulti-layer PCB to carry signals or power between the layers and traceson those layers. As such, high frequency signals may be carried alongthe vias through the PCB from one layer to another, or along the traceson the same or different layers. Unfortunately, a signal transmittedalong a via or trace may capacitively couple with/to another via ortrace that is located nearby. This capacitive coupling appears as noisein the signals being transmitted along the vias and traces. Somecoupling among vias and traces in the PCB may affect the performance ofthe circuit such that errors in the computing system occur. Indeed, thehigher the frequency of the signals, the higher, typically, isundesirable capacitive (and/or inductive) coupling and resulting errors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a block of two intermingled differentialvias disposed in a printed circuit board (PCB), according to an exampleembodiment.

FIG. 2 shows a perspective view of the block of two intermingleddifferential vias of FIG. 1 , according to an example embodiment.

FIGS. 3A and 3B are graphs showing, respectively, far end crosstalk andnear end crosstalk for the two intermingled differential vias of FIG. 1, according to an example embodiment.

FIG. 4 shows an array of blocks of intermingled differential viasdisposed on a PCB along with a naming convention to uniquely identifyeach individual via, according to an example embodiment.

FIG. 5 shows, from a top side of a PCB, an array of blocks ofintermingled differential vias disposed in the PCB with selected viasbackdrilled, according to an example embodiment.

FIG. 6 shows, from a bottom (opposite) side of the PCB of FIG. 5 , anarray of blocks of intermingled differential vias disposed in the PCBwith selected alternate vias backdrilled, according to an exampleembodiment.

FIGS. 7A and 7B are graphs showing, respectively, far end crosstalk andnear end crosstalk, and power sum crosstalk for a first selected victimin the array of blocks of intermingled differential vias as shown inFIG. 4 , according to an example embodiment.

FIGS. 8A and 8B are graphs showing, respectively, far end crosstalk andnear end crosstalk, and power sum crosstalk for a second selected victimin the array of blocks of intermingled differential vias as shown inFIG. 4 , according to an example embodiment.

FIGS. 9A and 9B are graphs showing, respectively, far end crosstalk andnear end crosstalk, and power sum crosstalk for a third and fourthselected victim in the array of blocks of intermingled differential viasas shown in FIG. 4 , according to an example embodiment.

FIG. 10 shows another array of blocks of intermingled differential viasdisposed in a PCB along with additional ground vias to further increaseisolation among the intermingled differential vias, according to anexample embodiment.

FIG. 11 shows still another possible arrangement of blocks ofintermingled differential vias disposed in a printed circuit board(PCB), according to an example embodiment.

FIG. 12 shows a via and trace architecture for a multi-layer PCB thatprovides an interlaced crosstalk controlled capacitor layout, accordingto an example embodiment.

FIG. 13 illustrates more clearly the narrow and wide via stances for thevia and trace architecture of FIG. 12 , according to an exampleembodiment.

FIGS. 14A and 14B are, respectively, top and bottom plan views oforthogonal capacitor placement on the multi-layer PCB for the interlacedcrosstalk controlled capacitor layout design, according to an exampleembodiment.

FIG. 15 shows alternating and offsetting blocks of the via and tracearchitecture, according to an example embodiment.

FIG. 16 is a graph showing powersum crosstalk at four victim blocks fromtwo aggressor blocks, according to an example embodiment.

FIG. 17 is a flowchart showing a series of operations for routing tracesin a multilayer printed circuit board, according to an exampleembodiment.

FIG. 18 illustrates a hardware block diagram of a computing device,according to an example embodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

Presented herein is a multilayer printed circuit board having a stackupincluding an upper half of the stackup and a lower half of the stackup,the multilayer printed circuit board having a top exposed surface and abottom exposed surface, a first trace and via structure, having oneportion disposed on the top exposed surface and another portion disposedwithin the upper half of the stackup, a second trace and via structure,having one portion disposed on the top exposed surface and anotherportion disposed within the upper half of the stackup, and firstelectrical components and second electrical components disposed on thetop exposed surface of the multilayer printed circuit board andassociated, respectively, with the first trace and via structure and thesecond trace and via structure, wherein the first electrical componentsare mounted orthogonally with respect to the second electricalcomponents.

In another embodiment, a method is provided that includes routing, on afirst internal layer of a printed circuit board, a first pair of tracesfrom a first trace and via structure between vias of a second trace andvia structure, routing, on a second internal layer of the printedcircuit board, a second pair of traces from the second trace and viastructure between vias of the first trace and via structure,backdrilling the vias of the first trace and via structure to a firstdepth, and backdrilling the vias of the second trace and via structureto a second depth that is deeper than the first depth.

In still another embodiment, a multilayer printed circuit board isdescribed and includes a stackup of layers including an upper half ofthe stackup and a lower half of the stackup, the multilayer printedcircuit board having a top exposed surface and a bottom exposed surface,and further having an array of blocks of intermingled differential viasdisposed in the multilayer printed circuit board.

Example Embodiments

Among computing or processing devices that employ a multi-layer printedcircuit board (PCB) is a serializer/deserializer (SERDES), typicallyimplemented as an integrated circuit that is mounted on the PCB. ASERDES is high speed communications device that converts data betweenserial data and parallel interfaces in each direction. The primary useof a SERDES is to provide data transmission over a single line or adifferential pair in order to minimize the number of I/O pins andinterconnects needed to communicate between computing devices that arespaced apart from one another.

Current and next generation SERDES rely on coupling capacitors tooperate. Given the frequencies at which a SERDES functions, crosstalkbetween the vias, traces, and capacitors themselves (including theirconnection terminals) that serve the SERDES in/on the multi-layer PCB isan issue. The techniques described herein help to control (i.e., reduce)crosstalk among multi-layer PCB structures while at the same timeoptimizing use of PCB real-estate. That is, as will be described morefully below with reference to the drawings, described herein aretechniques for arranging intermingled differential vias and providing anoverall via and trace architecture for a multi-layer PCB that provideseffective crosstalk reduction. Such techniques are useful in SERDESapplications as well as other applications where multiple vias, traces,and electrical components are densely arranged in/on a multi-layer PCB.

FIG. 1 shows a plan view of a block 100 of two intermingled differentialvias disposed in/on a printed circuit board (PCB) 150, according to anexample embodiment. As shown, a first differential via pair comprisingvias 110P (positive), 110N (negative) and a second differential via paircomprising vias 112P, 112N are arranged in a square pattern, e.g., witheach via centered on a respective vertex of a square. In thisconfiguration, the differential via pairs are electromagneticallybalanced in that, e.g., via 110P is equidistant from via 112P and via.112N. Likewise, via 110N is equidistant from vias 112P and 112N. As aresult, any interference picked up by vias 112P, 112N as a result: ofcrosstalk from vias 110P, 110N will be cancelled due to the propertiesof differential signals, i.e the same interference is cancelled out whenthe signals of the differential pair are subtracted from one another,

Also shown in FIG. 1 are ground vias 120. With such an arrangement, aground, signal, signal, ground (GSSG) architecture is realized, Inaccordance with the embodiments described herein, the signal-to-ground(S:G) ratio may be up to 36:16.

FIG. 2 shows a perspective or 3D view of the block of two intermingleddifferential vias of FIG. 1 , according to an example embodiment. In theembodiment shown, the vias 110P, 110N, 112P, 112N pass from a topmostlayer to a bottom-most layer of the PCB (not shown). However, as will bedescribed elsewhere, selected ones of those vias may be backdrilled fromeither the top 210 or the bottom 220 of the PCB. Such backdrillingfurther isolates signals from one another, thus still further reducingthe amount of crosstalk between differential pairs in the block 100 oftwo intermingled differential vias.

In the configuration shown in FIGS. 1 and 2 , the electromagneticinteractions among P and N of both differential vias 110P, 110N, 112P.112N are equal. Thus, it is expected that these two pairs have a minimalcoupling. Simulation results for a top to bottom intermingleddifferential vias verifies this prediction, More specifically, FIGS. 3Aand 3B are graphs showing, respectively, far end crosstalk (FEXT) andnear end crosstalk (NEXT) for the two intermingled differential vias ofFIG. 1 , according to an example embodiment. As shown, FEXT and NEXT forthis system is as low as −40 dB even for frequencies up to 45 GHz.

FIG. 4 shows an array 400 of blocks 100 of intermingled differentialvias disposed on a PCB along with a naming convention to uniquelyidentify each individual via, according to an example embodiment. Asshown, each block 100 is arranged adjacent another block 100, in acheckerboard layout, where ground vias 120 are shared by adjacent blocks100. Such an array 400 can be disposed on a PCB next to an integratedcircuit, such as a SERDES. In one implementation, via-to-via spacing is32 mil, and eighteen differential vias can be placed in a 288×288 milsquare space on the PCB. The eighteen vias, in the depicted embodiment,are organized into nine blocks 100, with three rows and three columns.The top left block is in row 1 column 1, and thus the vias in that blockare designated as 11 p, 11 n, 11 ps (second), 11 ns (second), The topright block 100 is in row 1, column 3, and thus the vias in that blockare designated as 13 p, 13 n, 13 ps (second), 13 ns (second). The bottomright block 100 is in row 3, column 3, and thus the vias in that blockare designated as 33 p, 33 n, 33 ps (second), 33 ns (second). Theintervening blocks include 12 p, 12 n, 12 ps, 12 ns, 13 p, 13 n, 13 ps,13 ns, 21 p, 21 n, 21 ps, 21 ns, 22 n, 22 ps, 22 ns, 23 p, 23 n, 23 ps,23 ns, 31 p, 31 n, 31 ps, 31 ns, 32 p, 32 n, 32 ps, and 32 ns. Thesignal-to-ground (S:G) ratio may thus be easily seen to be 36:16 in thisembodiment.

In the arrangement of FIG. 4 , adjacent blocks 100 are considered to bethe main aggressors. Thus, in order to further reduce crosstalk amongadjacent blocks 100, the PCB is configured to alternate the layer usagebetween a top half and a bottom half stackup in adjacent differentialblocks. This arrangement is shown in FIGS. 5 and 6 .

That is, FIG. 5 shows, from a top side of a PCB, an array 400 of blocks100 of intermingled differential vias disposed in the PCB with selectedvias backdrilled, according to an example embodiment. In thisembodiment, the blocks 100 are designated generally by row, column,e.g., 1,1 for the top left block 100, and 3,3 for the bottom right block100. In this case, the vias associated with blocks 100 1,2, 2,1, 2,3,and 3,2 are backdrilled from the top such that the closest aggressorblock 100 is arranged diagonally from a given victim block 100.

FIG. 6 shows, from a bottom (opposite) side of the PCB of FIG. 5 , anarray 400 of blocks 100 of intermingled differential vias disposed inthe PCB with selected alternate vias backdrilled, according to anexample embodiment. That is, from a bottom view of the PCB, and, e.g.,directly underneath the pattern shown in FIG. 5 , blocks 100 1,1, 1,3,2,2, 3,1, and 3,3 are backdrilled. In this, away, differential vias areseparated not only in a planar dimension, but also by a depth dimension.

Due to symmetry, only three measures of powersum crosstalk are needed toanalyze the backdrilled arrangement of FIGS. 5 and 6 : a) diff (2,2)(with worst case crosstalk), b) diff (1,1), and c) diff (1,2).

FIGS. 7A and 7B are graphs showing, respectively, far end crosstalk andnear end crosstalk (and powersum crosstalk) for a first selected victim,i.e., 2,2, in the array 400 of blocks 100 of intermingled differentialvias as shown in FIG. 4 , according to an example embodiment.

FIGS. 8A and 8B are graphs showing, respectively, far end crosstalk andnear end crosstalk (and powersum crosstalk) for a second selectedvictim, i.e., 1,1, in the array 400 of blocks 100 of intermingleddifferential vias as shown in FIG. 4 , according to an exampleembodiment.

FIGS. 9A and 9B are graphs showing, respectively, far end crosstalk andnear end crosstalk (and powersum crosstalk) for a third and fourthselected victim, i.e., 1,2 and 2,1, in the array 400 of blocks 100 ofintermingled differential vias as shown in FIG. 4 , according to anexample embodiment.

The simulation resulting in the graphs of FIGS. 7A, 7B, 8A, 8B, 9A, and9B was conducted on a half stackup height of 68 mils. In an actualimplementation, the crosstalk may be even less than what is shown inFIGS. 7A, 7B, 8A, 8B, 9A, and 9B because the heights of the vias may beshorter.

FIG. 10 shows another array 1000 of blocks of intermingled differentialvias disposed in a PCB along with additional ground vias to furtherincrease isolation among the intermingled differential vias, accordingto an example embodiment. That is, in FIG. 10 ground vias 120 fullysurround each block 100 of intermingled differential vias. While thisapproach decreases the S:G ratio, additional isolation can be achieved.

FIGS. 11 shows still another possible arrangement of a block 1100 ofintermingled differential vias disposed in a printed circuit board(PCB), according to an example embodiment. In this approach, twoadditional pairs of intermingled differential vias 1110P, 1110N, 1112P,1112N are disposed symmetrically around block 100 of intermingleddifferential vias 110P, 110N, 112P, 112N. And, with the use ofappropriate backdrilling, selected ones of these vias may be disposedonly in a top half of a PCB stackup, while the remaining ones of thesevias may be disposed only in a bottom half of the PCB stackup. Due tothe symmetrical layout, the same advantages associated with reducedcrosstalk are achieved.

Thus, those skilled in the art will appreciate that a density optimizedarray of transition vias is disclosed. With such a layout, 18 additionalvia pairs or 36 total differential vias (72 vias in total) can be placedon a PCB in a 480×480 mil square space. The ratio of signal-to-groundvia usage is as high as 72:16, resulting in a compact design, and withfewer holes on power layers. The powersum crosstalk for this case isalso extremely low.

In addition to the blocks 100, 1100 of intermingled differential viasdescribed above, also described herein is an Interlaced CrosstalkControlled (ICC) capacitor layout design. As will be evident to thoseskilled in the art, the disclosed ICC capacitor layout design leveragesblocks of eight capacitors (i.e., four differential pair channels)co-located on the top and bottom of a PCB in a same predetermined area.Several factors are considered in connection with this layout design: a)minimum allowed spacing based on predetermined fabrication rules, b)routing (and power) friendly breakout into a ball grid array (BGA) pinfield for, e.g., a SERDES device, c) optimized insertion loss by usingsolid ground references (GSSG), and d) achieving low crosstalk usingvarious approaches discussed below.

In order to crosstalk isolate channels on opposite sides of a multilayerPCB stackup (i.e., isolate channels with capacitors on a top layer fromchannels with capacitors on a bottom layer), the embodiments describedherein use a “layer utilization strategy.” Capacitors placed on the top(exposed) side of the PCB use the upper half of the stackup for routing,and capacitors placed on the bottom (exposed) side of the PCB use thebottom half of the stackup for routing. By backdrilling and top drilling(i.e. backdrilling from a top side of the PCB) selected vias, thesignals on the topside are effectively isolated from those on the bottomside, thus reducing crosstalk, where crosstalk coupling may be <˜−80 dB.

FIG. 12 shows a via and trace architecture for a multi-layer PCB 1200that provides an ICC capacitor layout design, according to an exampleembodiment. As can be seen, several strategies are employed tocrosstalk-isolate channels for capacitors on a same side of the PCB 1200(within a same block of capacitors). Capacitors on the top side of thePCB are crosstalk-isolated by using geometrical orthogonality inplacement of differential vias (FIG. 12 ). FIG. 13 shows another view ofthe overall ICC capacitor layout design, without ground vias, and a 180degree rotation compared to FIG. 12 . Capacitors on the bottom side ofthe PCB 1200 are crosstalk isolated by using predetermined separation(FIGS. 14A and 14B).

More specifically, FIG. 12 shows four different via and tracestructures, including first structure 1210, second structure 1310, thirdstructure 1410, and fourth structure 1510. First structure 1210 includesvias 1211, 1212, 1213, 1214, which are arranged to be electricallyconnected to traces 1215, on a top side of a PCB 1200, that areconfigured to terminate in pads on which capacitors 1217, 1218 aremounted (i.e., soldered to the PCB 1200). Internal layers of the PCB1200 include traces 1220, 1221, 1222, 1223 that are electricallyconnected to vias 1211, 1212, 1213, 1214, as shown. Traces 1215 of firststructure 1210 extend substantially along a Y-axis of PCB 1200 such thatcapacitors 1217, 1218 are oriented along the Y-axis when mounted. Also,as can be seen, the vias 1211, 1212, 1213, 1214 of first structure 1210are arranged with a relative wide stance in the Y-axis direction,allowing other traces to more easily be routed between vias 1211, 1212,1213, 1214.

Second structure 1310 includes vias 1311, 1312, which are arranged to beelectrically connected to traces 1315, on a top side of a PCB 1200, thatare configured to end in pads on which capacitors 1317, 1318 are mounted(i.e., soldered to the PCB 1200). Internal layers of the PCB 1200include traces 1320, 1321 that are electrically connected to vias 1311,1312, as shown. Traces 1315 of second structure 1310 extendsubstantially along the X-axis such that capacitors 1317, 1318 areoriented along the X-axis when mounted. Also, as can be seen, the vias1311, 1312 of second structure 1310 are arranged with a relativelynarrow stance in the Y-axis direction.

Third structure 1410 includes vias 1411, 1412, which are arranged to beelectrically connected to traces 1415, on a bottom side of PCB 1200,that are configured to end in pads on which capacitors 1417, 1418 aremounted (i.e., soldered to PCB 1200). Internal layers of PCB 1200include traces 1420, 1421 that are electrically connected to vias 1411,1412, as shown. Traces 1415 of third structure 1410 are arranged suchthat capacitors 1417, 1418 are oriented along the X-axis when mounted.Also, as can be seen, the vias 1411, 1412 of third structure 1410 arearranged with a relatively wide stance in the Y-axis direction, allowingother traces to more easily be routed between vias 1411, 1412.

Fourth structure 1510 includes vias 1511, 1512, 1513, 1514, which arearranged to be electrically connected to traces 1515, on a bottom sideof a PCB 1200, that are configured to terminate in pads on whichcapacitors 1517, 1518 are mounted (i.e., soldered to PCB 1200). Internallayers of the PCB 1200 include traces 1520, 1521, 1522, 1523 that areelectrically connected to vias 1511, 1512, 1513, 1514, as shown. Traces1515 of fourth structure 1510 extend substantially along the X-axis ofPCB 1200 such that capacitors 1517, 1518 are oriented along the X-axiswhen mounted. Also, as can be seen, the vias 1511, 1512, 1513, 1514 offourth structure 1510 are arranged with a relative wide stance in theX-axis direction.

As can be seen in FIG. 12 (and FIG. 13 ) the vias are truncated, i.e.,backdrilled at least halfway into the stackup of the PCB 1200, from thetop or bottom, as the case may be. Indeed, different pairs of vias maybe backdrilled to different depths compared to other pairs of vias. Forexample, vias 1211, 1212, 1213, 1214 are all backdrilled to the samedepth, whereas vias 1311, 1312 are backdrilled closer to a top exposedsurface of the PCB 1200. Also, ground vias 1280 are provided throughoutthe layout design of the PCB 1200 to ensure a GSSG configuration.

In an embodiment, aggressor traces such as traces 1522, 1523 associatedwith fourth structure 1510 are routed through the wide stance of victimvias, e.g., vias 1411, 1412 of third structure 1410 where thetrace-to-via spacing is more significant.

Also, aggressor traces, such as traces 1420, 1421 are routed atbackdrilled region of the narrow stance of a victim channel handled byfourth structure 1510. That is, vias 1511, 1512, 1513, 1514 arebackdrilled to below a level of traces 1420, 1421. As such, there islittle to no via-to-trace crosstalk for closely spaced via to tracecases.

FIG. 13 illustrates more clearly the narrow and wide via stances for thevia and trace architecture of FIG. 12 . Note that ground vias 1280 arenot shown in FIG. 13 . Further, the first structure 1210, secondstructure 1310, third structure 1410, and fourth structure 1510 aretogether rotated by 180 degrees compared to the view shown in FIG. 12 .

FIGS. 14A and 1413 are, respectively, top and bottom plan views oforthogonal capacitor placement on the multi-layer PCB for the interlacedcrosstalk controlled capacitor layout design, according to an exampleembodiment, As shown, on a top side of PCB 1200 capacitors 1217, 1218are oriented orthogonally with respect to capacitors 1317, 1318.Similarly, on a bottom side of PCB 1200, capacitors 1417, 1418 areoriented orthogonally with respect to capacitors 1517, 1518.

Those skilled in the art will appreciate that the via and tracearchitecture described herein is routing friendly in the verticaldirection as shown in FIGS. 14A and 14B. This is accomplished bydifferential pairs being narrow enough to fit in between capacitor vias.

FIG. 15 shows alternating and offsetting blocks of the via and tracearchitecture, according to an example embodiment. That is, when placingseveral via and trace structures beside each other, it may beadvantageous to alternate from top to bottom first structure 1210,second structure1310, third structure1410, fourth structure 1510 as wellas offsetting those structures, resulting in a pattern ABABAB as shownin FIG. 15 . This approach reproduces the desirable geometricorthogonality that helps to reduce crosstalk. Also, the illustratedarrangement helps to leverage the top and bottom layer of the stackup ofthe PCB 1200 to breakout to the first row of capacitors with no vias.

FIG. 16 is a graph showing powersum crosstalk at four victim blocks fromtwo aggressor blocks, according to an example embodiment. As is evidentfrom the figure, the achieved powersum crosstalk is −40 dB up to 29 GHz,with 8 aggressor channels for each victim).

Although not expressly shown, PCB 1200 may also incorporate the blocksof two intermingled differential vias described in connection with FIGS.1-11 .

FIG. 17 is a flowchart showing a series of operations 1700 for routingtraces in a multilayer printed circuit board, according to an exampleembodiment. At 1710, an operation includes routing, on a first internallayer of a printed circuit board, a first pair of traces from a firsttrace and via structure between vias of a second trace and viastructure. At 1712, an operation routing, on a second internal layer ofthe printed circuit board, a second pair of traces from the second traceand via structure between vias of the first trace and via structure. At1714. an operation includes backdrilling the vias of the first trace andvia structure to a first depth. And, at 1716, an operation includesbackdrilling the vias of the second trace and via structure to a seconddepth that is deeper than the first depth.

FIG. 18 illustrates a hardware block diagram of a computing device 1800that may be employed to design the multilayer printed circuit boarddescribed herein, or that might incorporate the multilayer PCB describedherein.

In at least one embodiment, the computing device 1800 may include one ormore processor(s) 1802, one or more memory element(s) 1804, storage1806, a bus 1808, one or more network processor unit(s) 1810interconnected with one or more network input/output (I/O) interface(s)1812, one or more I/O interface(s) 1814, and control logic 1820. Invarious embodiments, instructions associated with logic for computingdevice 1800 can overlap in any manner and are not limited to thespecific allocation of instructions and/or operations described herein.

In at least one embodiment, processor(s) 1802 is/are at least onehardware processor configured to execute various tasks, operationsand/or functions for computing device 1800 as described herein accordingto software and/or instructions configured for computing device 1800.Processor(s) 1802 (e.g., a hardware processor) can execute any type ofinstructions associated with data to achieve the operations detailedherein. In one example, processor(s) 1802 can transform an element or anarticle (e.g., data, information) from one state or thing to anotherstate or thing. Any of potential processing elements, microprocessors,digital signal processor, baseband signal processor, modem, PHY,controllers, systems, managers, logic, and/or machines described hereincan be construed as being encompassed within the broad term ‘processor’.

In at least one embodiment, memory element(s) 1804 and/or storage 1806is/are configured to store data, information, software, and/orinstructions associated with computing device 1800, and/or logicconfigured for memory element(s) 1804 and/or storage 1806. For example,any logic described herein (e.g., control logic 1820) can, in variousembodiments, be stored for computing device 1800 using any combinationof memory element(s) 1804 and/or storage 1806. Note that in someembodiments, storage 1806 can be consolidated with memory element(s)1804 (or vice versa), or can overlap/exist in any other suitable manner.

In at least one embodiment, bus 1808 can be configured as an interfacethat enables one or more elements of computing device 1800 tocommunicate in order to exchange information and/or data. Bus 1808 canbe implemented with any architecture designed for passing control, dataand/or information between processors, memory elements/storage,peripheral devices, and/or any other hardware and/or software componentsthat may be configured for computing device 1800. In at least oneembodiment, bus 1808 may be implemented as a fast kernel-hostedinterconnect, potentially using shared memory between processes (e.g.,logic), which can enable efficient communication paths between theprocesses.

In various embodiments, network processor unit(s) 1810 may enablecommunication between computing device 1800 and other systems, entities,etc., via network I/O interface(s) 1812 to facilitate operationsdiscussed for various embodiments described herein. In variousembodiments, network processor unit(s) 1810 can be configured as acombination of hardware and/or software, such as one or more Ethernetdriver(s) and/or controller(s) or interface cards, Fibre Channel (e.g.,optical) driver(s) and/or controller(s), and/or other similar networkinterface driver(s) and/or controller(s) now known or hereafterdeveloped to enable communications between computing device 1800 andother systems, entities, etc. to facilitate operations for variousembodiments described herein. In various embodiments, network I/Ointerface(s) 1812 can be configured as one or more Ethernet port(s),Fibre Channel ports, and/or any other I/O port(s) now known or hereafterdeveloped. Thus, the network processor unit(s) 1810 and/or network I/Ointerface(s) 1812 may include suitable interfaces for receiving,transmitting, and/or otherwise communicating data and/or information ina network environment.

interface(s) 1814 allow for input and output of data and/or informationwith other entities that may be connected to computing device 1800. Forexample, I/O interface(s) 1814 may provide a connection to externaldevices such as a keyboard, keypad, a touch screen, and/or any othersuitable input and/or output device now known or hereafter developed. Insome instances, external devices can also include portable computerreadable (non-transitory) storage media such as database systems, thumbdrives, portable optical or magnetic disks, and memory cards. In stillsome instances, external devices can be a mechanism to display data to auser, such as, for example, a computer monitor, a display screen, or thelike.

In various embodiments, control logic 1820 can include instructionsthat, when executed, cause processor(s) 1802 to perform operations,which can include, but not be limited to, providing overall controloperations of computing device; interacting with other entities,systems, etc. described herein; maintaining and/or interacting withstored data, information, parameters, etc. (e.g., memory element(s),storage, data structures, databases, tables, etc.); combinationsthereof; and/or the like to facilitate various operations forembodiments described herein.

The programs described herein (e.g., control logic 1820) may beidentified based upon application(s) for which they are implemented in aspecific embodiment. However, it should be appreciated that anyparticular program nomenclature herein is used merely for convenience;thus, embodiments herein should not be limited to use(s) solelydescribed in any specific application(s) identified and/or implied bysuch nomenclature.

In various embodiments, entities as described herein may storedata/information in any suitable volatile and/or non-volatile memoryitem (e.g., magnetic hard disk drive, solid state hard drive,semiconductor storage device, random access memory (RAM), read onlymemory (ROM), erasable programmable read only memory (EPROM),application specific integrated circuit (ASIC), etc.), software, logic(fixed logic, hardware logic, programmable logic, analog logic, digitallogic), hardware, and/or in any other suitable component, device,element, and/or object as may be appropriate. Any of the memory itemsdiscussed herein should be construed as being encompassed within thebroad term ‘memory element’. Data/information being tracked and/or sentto one or more entities as discussed herein could be provided in anydatabase, table, register, list, cache, storage, and/or storagestructure: all of which can be referenced at any suitable timeframe. Anysuch storage options may also be included within the broad term ‘memoryelement’ as used herein.

Note that in certain example implementations, operations as set forthherein may be implemented by logic encoded in one or more tangible mediathat is capable of storing instructions and/or digital information andmay be inclusive of non-transitory tangible media and/or non-transitorycomputer readable storage media (e.g., embedded logic provided in: anASIC, digital signal processing (DSP) instructions, software(potentially inclusive of object code and source code), etc.) forexecution by one or more processor(s), and/or other similar machine,etc. Generally, memory element(s) 1804 and/or storage 1806 can storedata, software, code, instructions (e.g., processor instructions),logic, parameters, combinations thereof, and/or the like used foroperations described herein. This includes memory element(s) 1804 and/orstorage 1806 being able to store data, software, code, instructions(e.g., processor instructions), logic, parameters, combinations thereof,or the like that are executed to carry out operations in accordance withteachings of the present disclosure.

In some instances, software of the present embodiments may be availablevia a non-transitory computer useable medium (e.g., magnetic or opticalmediums, magneto-optic mediums, CD-ROM, DVD, memory devices, etc.) of astationary or portable program product apparatus, downloadable file(s),file wrapper(s), object(s), package(s), container(s), and/or the like.In some instances, non-transitory computer readable storage media mayalso be removable. For example, a removable hard drive may be used formemory/storage in some implementations. Other examples may includeoptical and magnetic disks, thumb drives, and smart cards that can beinserted and/or otherwise connected to a computing device for transferonto another computer readable storage medium.

Variations and Implementations

Embodiments described herein may include one or more networks, which canrepresent a series of points and/or network elements of interconnectedcommunication paths for receiving and/or transmitting messages (e.g.,packets of information) that propagate through the one or more networks.These network elements offer communicative interfaces that facilitatecommunications between the network elements. A network can include anynumber of hardware and/or software elements coupled to (and incommunication with) each other through a communication medium. Suchnetworks can include, but are not limited to, any local area network(LAN), virtual LAN (VLAN), wide area network (WAN) (e.g., the Internet),software defined WAN (SD-WAN), wireless local area (WLA) access network,wireless wide area (WWA) access network, metropolitan area network(MAN), Intranet, Extranet, virtual private network (VPN), Low PowerNetwork (LPN), Low Power Wide Area Network (LPWAN), Machine to Machine(M2M) network, Internet of Things (IoT) network, Ethernetnetwork/switching system, any other appropriate architecture and/orsystem that facilitates communications in a network environment, and/orany suitable combination thereof.

Networks through which communications propagate can use any suitabletechnologies for communications including wireless communications (e.g.,4G/5G/nG, IEEE 802.11 (e.g., Wi-Fi®/Wi-Fi6®), IEEE 802.16 (e.g.,Worldwide Interoperability for Microwave Access (WiMAX)),Radio-Frequency Identification (RFID), Near Field Communication (NFC),Bluetooth™, mm·wave, Ultra-Wideband (UWB), etc.), and/or wiredcommunications (e.g., T1 lines, T3 lines, digital subscriber lines(DSL), Ethernet, Fibre Channel, etc.). Generally, any suitable means ofcommunications may be used such as electric, sound, light, infrared,and/or radio to facilitate communications through one or more networksin accordance with embodiments herein. Communications, interactions,operations, etc. as discussed for various embodiments described hereinmay be performed among entities that may directly or indirectlyconnected utilizing any algorithms, communication protocols, interfaces,etc. (proprietary and/or non-proprietary) that allow for the exchange ofdata and/or information.

In various example implementations, entities for various embodimentsdescribed herein can encompass network elements (which can includevirtualized network elements, functions, etc.) such as, for example,network appliances, forwarders, routers, servers, switches, gateways,bridges, load balancers, firewalls, processors, modules, radioreceivers/transmitters, or any other suitable device, component,element, or object operable to exchange information that facilitates orotherwise helps to facilitate various operations in a networkenvironment as described for various embodiments herein. Note that withthe examples provided herein, interaction may be described in terms ofone, two, three, or four entities. However, this has been done forpurposes of clarity, simplicity and example only. The examples providedshould not limit the scope or inhibit the broad teachings of systems,networks, etc. described herein as potentially applied to a myriad ofother architectures.

Communications in a network environment can be referred to herein as‘messages’, ‘messaging’, ‘signaling’, ‘data’, ‘content’, ‘objects’,‘requests’, ‘queries’, ‘responses’, ‘replies’, etc. which may beinclusive of packets. As referred to herein and in the claims, the term‘packet’ may be used in a generic sense to include packets, frames,segments, datagrams, and/or any other generic units that may be used totransmit communications in a network environment. Generally, a packet isa formatted unit of data that can contain control or routing information(e.g., source and destination address, source and destination port,etc.) and data, which is also sometimes referred to as a ‘payload’,‘data payload’, and variations thereof. In some embodiments, control orrouting information, management information, or the like can be includedin packet fields, such as within header(s) and/or trailer(s) of packets.Internet Protocol (IP) addresses discussed herein and in the claims caninclude any IP version 4 (IPv4) and/or IP version 6 (IPv6) addresses.

To the extent that embodiments presented herein relate to the storage ofdata, the embodiments may employ any number of any conventional or otherdatabases, data stores or storage structures (e.g., files, databases,data structures, data or other repositories, etc.) to store information.

Note that in this Specification, references to various features (e.g.,elements, structures, nodes, modules, components, engines, logic, steps,operations, functions, characteristics, etc.) included in ‘oneembodiment’, ‘example embodiment’, ‘an embodiment’, ‘anotherembodiment’, ‘certain embodiments’, ‘some embodiments’, ‘variousembodiments’, ‘other embodiments’, ‘alternative embodiment’, and thelike are intended to mean that any such features are included in one ormore embodiments of the present disclosure, but may or may notnecessarily be combined in the same embodiments. Note also that amodule, engine, client, controller, function, logic or the like as usedherein in this Specification, can be inclusive of an executable filecomprising instructions that can be understood and processed on aserver, computer, processor, machine, compute node, combinationsthereof, or the like and may further include library modules loadedduring execution, object files, system files, hardware logic, softwarelogic, or any other executable modules.

It is also noted that the operations and steps described with referenceto the preceding figures illustrate only some of the possible scenariosthat may be executed by one or more entities discussed herein. Some ofthese operations may be deleted or removed where appropriate, or thesesteps may be modified or changed considerably without departing from thescope of the presented concepts. In addition, the timing and sequence ofthese operations may be altered considerably and still achieve theresults taught in this disclosure. The preceding operational flows havebeen offered for purposes of example and discussion. Substantialflexibility is provided by the embodiments in that any suitablearrangements, chronologies, configurations, and timing mechanisms may beprovided without departing from the teachings of the discussed concepts.

As used herein, unless expressly stated to the contrary, use of thephrase ‘at least one of’, ‘one or more of’, ‘and/or’, variationsthereof, or the like are open-ended expressions that are bothconjunctive and disjunctive in operation for any and all possiblecombination of the associated listed items. For example, each of theexpressions ‘at least one of X, Y and Z’, ‘at least one of X, Y or Z’,‘one or more of X, Y and Z’, ‘one or more of X, Y or Z’ and ‘X, Y and/orZ’ can mean any of the following: 1) X, but not Y and not Z; 2) Y, butnot X and not Z; 3) Z, but not X and not Y; 4) X and Y, but not Z; 5) Xand Z, but not Y; 6) Y and Z, but not X; or 7) X, Y, and Z.

Additionally, unless expressly stated to the contrary, the terms‘first’, ‘second’, ‘third’, etc., are intended to distinguish theparticular nouns they modify (e.g., element, condition, node, module,activity, operation, etc.). Unless expressly stated to the contrary, theuse of these terms is not intended to indicate any type of order, rank,importance, temporal sequence, or hierarchy of the modified noun. Forexample, ‘first X’ and ‘second X’ are intended to designate two ‘X’elements that are not necessarily limited by any order, rank,importance, temporal sequence, or hierarchy of the two elements. Furtheras referred to herein, ‘at least one of’ and ‘one or more of’ can berepresented using the ‘(s)’ nomenclature (e.g., one or more element(s)).

In sum, an apparatus is provided. The apparatus includes a multilayerprinted circuit board comprising a stackup including an upper half ofthe stackup and a lower half of the stackup, the multilayer printedcircuit board having a top exposed surface and a bottom exposed surface,a first trace and via structure, having one portion disposed on the topexposed surface and another portion disposed within the upper half ofthe stackup, a second trace and via structure, having one portiondisposed on the top exposed surface and another portion disposed withinthe upper half of the stackup, and first electrical components andsecond electrical components disposed on the top exposed surface of themultilayer printed circuit board and associated, respectively, with thefirst trace and via structure and the second trace and via structure,wherein the first electrical components are mounted orthogonally withrespect to the second electrical components.

The first vias of the first trace and via structure may be separated bya first distance and second vias of the second trace and via structuremay be separated by a second distance that is less than the firstdistance

The first traces of the first trace and via structure may pass betweenthe second vias of the second trace and via structure, and second tracesof the second trace and via structure may pass between the first vias ofthe first trace and via structure.

The first trace and via structure may only be disposed in the upper halfof the stackup, and the second trace and via structure may only bedisposed only in the upper half of the stackup.

The apparatus may further include a third trace and via structure,having one portion disposed on the bottom exposed surface and anotherportion disposed within the lower half of the stackup, a fourth traceand via structure, having one portion disposed on the bottom exposedsurface and another portion disposed within the lower half of thestackup, and third electrical components and fourth electricalcomponents disposed on the bottom exposed surface of the multilayerprinted circuit board and associated, respectively, with the third traceand via structure and the fourth trace and via structure, wherein atleast one of the third electrical components and the fourth electricalcomponents are mounted orthogonally to the first electrical components

The third trace and via structure and fourth trace and via structure maybe disposed (e.g., directly) opposite the first trace and via structureand the second trace and via structure.

The third trace and via structure and fourth trace and via structure maybe disposed opposite, and offset from, the first trace and via structureand the second trace and via structure.

At least one of the first electrical components, second electricalcomponents, third electrical components, and fourth electricalcomponents include capacitors.

The apparatus may further include a plurality of ground vias. Theplurality of ground vias may be arranged with first vias of the firsttrace and via structure and second vias of the second trace and viastructure to provide a ground-signal-signal-ground (GSSG) arrangement.

The first vias of the first trace and via structure and second vias ofthe second trace and via structure may be configured to carrydifferential signals.

In an embodiment, first vias of the first trace and via structure have afirst length and second vias of the second trace and via structure havea second length shorter than the first length.

The apparatus may still further include a block of intermingleddifferential vias. The block of intermingled differential vias mayinclude two pairs of differential vias arranged in a square pattern,with each via of each pair of differential vias centered on a respectivevertex of the square pattern.

In another embodiment, a method is provided. The method may includerouting, on a first internal layer of a printed circuit board, a firstpair of traces from a first trace and via structure between vias of asecond trace and via structure, routing, on a second internal layer ofthe printed circuit board, a second pair of traces from the second traceand via structure between vias of the first trace and via structure,backdrilling the vias of the first trace and via structure to a firstdepth, and backdrilling the vias of the second trace and via structureto a second depth that is deeper than the first depth.

The method may further include mounting first capacitors in a firstdirection on the printed circuit board and electrically connected to thefirst trace and via structure, and mounting second capacitors in asecond direction, orthogonal to the first direction, on the printedcircuit board and electrically connected to the second trace and viastructure.

In still another embodiment, an apparatus includes a multilayer printedcircuit board comprising a stackup of layers including an upper half ofthe stackup and a lower half of the stackup, the multilayer printedcircuit board having a top exposed surface and a bottom exposed surface,and an array of blocks of intermingled differential vias disposed in themultilayer printed circuit board.

In an implementation, each block in the array of blocks of intermingleddifferential vias includes two pairs of differential vias arranged in asquare pattern, with each via of each pair of differential vias centeredon a respective vertex of the square pattern.

The apparatus may further include ground vias that extend between thetop exposed surface and the bottom exposed surface, the ground viasbeing spaced symmetrically around each block in the array of blocks ofintermingled differential vias. A signal via-to-ground via (S:G via)ratio is up to 72:16.

One or more advantages described herein are not meant to suggest thatany one of the embodiments described herein necessarily provides all ofthe described advantages or that all the embodiments of the presentdisclosure necessarily provide any one of the described advantages.Numerous other changes, substitutions, variations, alterations, and/ormodifications may be ascertained to one skilled in the art and it isintended that the present disclosure encompass all such changes,substitutions, variations, alterations, and/or modifications as fallingwithin the scope of the appended claims.

What is claimed is:
 1. An apparatus comprising: a multilayer printedcircuit board comprising a stackup including an upper half of thestackup and a lower half of the stackup, the multilayer printed circuitboard having a top exposed surface and a bottom exposed surface; a firsttrace and via structure, having one portion disposed on the top exposedsurface and another portion disposed within the upper half of thestackup; a second trace and via structure, having one portion disposedon the top exposed surface and another portion disposed within the upperhalf of the stackup; and first electrical components and secondelectrical components disposed on the top exposed surface of themultilayer printed circuit board and associated, respectively, with thefirst trace and via structure and the second trace and via structure,wherein the first electrical components are mounted orthogonally withrespect to the second electrical components, wherein first vias of thefirst trace and via structure are separated by a first distance andsecond vias of the second trace and via structure are separated by asecond distance that is less than the first distance, wherein firsttraces of the first trace and via structure pass between the second viasof the second trace and via structure, and second traces of the secondtrace and via structure pass between the first vias of the first traceand via structure, wherein the first electrical components overlie thesecond traces of the second trace and via structure, and wherein thefirst traces of the first trace and via structure exposed on the topexposed surface, and to which the first electrical components areconnected, are orthogonal to the second traces of the second trace andvia structure.
 2. The apparatus of claim 1, wherein the first trace andvia structure is disposed only in the upper half of the stackup, and thesecond trace and via structure is disposed only in the upper half of thestackup.
 3. The apparatus of claim 1, further comprising: a third traceand via structure, having one portion disposed on the bottom exposedsurface and another portion disposed within the lower half of thestackup; a fourth trace and via structure, having one portion disposedon the bottom exposed surface and another portion disposed within thelower half of the stackup; and third electrical components and fourthelectrical components disposed on the bottom exposed surface of themultilayer printed circuit board and associated, respectively, with thethird trace and via structure and the fourth trace and via structure,wherein at least one of the third electrical components and the fourthelectrical components are mounted orthogonally to the first electricalcomponents.
 4. The apparatus of claim 3, wherein the third trace and viastructure and fourth trace and via structure are disposed opposite thefirst trace and via structure and the second trace and via structure. 5.The apparatus of claim 3, wherein the third trace and via structure andfourth trace and via structure are disposed opposite, and offset from,the first trace and via structure and the second trace and viastructure.
 6. The apparatus of claim 1, wherein at least one of thefirst electrical components, second electrical components, thirdelectrical components, and fourth electrical components comprisecapacitors.
 7. The apparatus of claim 1, further comprising a pluralityof ground vias.
 8. The apparatus of claim 7, wherein the plurality ofground vias are arranged with first vias of the first trace and viastructure and second vias of the second trace and via structure toprovide a ground-signal-signal-ground (GSSG) arrangement.
 9. Theapparatus of claim 1, wherein first vias of the first trace and viastructure and second vias of the second trace and via structure carrydifferential signals.
 10. The apparatus of claim 1, wherein first viasof the first trace and via structure have a first length and second viasof the second trace and via structure have a second length shorter thanthe first length.
 11. The apparatus of claim 1, further comprising ablock of intermingled differential vias.
 12. The apparatus of claim 11,wherein the block of intermingled differential vias comprises two pairsof differential vias arranged in a square pattern, with each via of eachpair of differential vias centered on a respective vertex of the squarepattern.
 13. The apparatus of claim 1, wherein vias of the first raceand via structure are backdrilled to a first depth; and vias of thesecond trace and via structure are backdrilled to a second depth that isdeeper than the first depth.
 14. An apparatus comprising: a multilayerprinted circuit board comprising a stackup including an upper half ofthe stackup and a lower half of the stackup, the multilayer printedcircuit board having a top exposed surface and a bottom exposed surface;a first trace and via structure, having one portion disposed on the topexposed surface and another portion disposed within the upper half ofthe stackup; a second trace and via structure, having one portiondisposed on the top exposed surface and another portion disposed withinthe upper half of the stackup; and first electrical components andsecond electrical components disposed on the top exposed surface of themultilayer printed circuit board and associated, respectively, with thefirst trace and via structure and the second trace and via structure,wherein the first electrical components are mounted to traces that arearranged orthogonally to, and that overlie, traces in the second traceand via structure that are disposed within the upper half of thestackup.